Underwater Sardine Dance

Canned sardines in supermarkets may actually be "sprat" (such as the “brisling sardine”) or round herrings. Fish sizes vary by species. Good quality sardines should have the head and gills removed before packing. They may also be eviscerated before packing (typically the larger varieties). If not, they should be purged of undigested or partially digested food or feces by holding the live fish in a tank long enough for them to empty their digestive systems.
In popular culture
Sardines are typically tightly packed in a small can which is scored for easy opening, either with a pull tab (similar to how a beverage can is opened), or a key, attached to the side of the can. Thus, it has the virtues of being an easily portable, nonperishable, self-contained food. The close packing of sardines in the can has led to their metaphorical use for any situation where people or objects are crowded together, for instance, in a bus or subway car. It has also been used as the name of a children's game, where one child hides and each successive child who finds the hidden one packs into the space until there is only one left out, who becomes the next one to hide.